ARACHNIDA. 647 



round this till it takes the form of a cup ; it is at this 

 stage of the work that it begins to lay its eggs in the cup, 

 and not content to iill it up to the brim, it also piles up 

 a large round heap, as high as the cup is deep. Here, 

 then, is a cup full of eggs, the under half covered and pro- 

 tected by the silken sides of the cup, but the ujDper still 

 bare and exposed to the air and the cold. She now sets 

 to vvork to cover these also : the process is similar to the pre- 

 ceding, that is, she weaves a thick web of silk all round 

 them, and, instead of a cup-shaped nest, like some birds, 

 the whole partakes of tlie form of a ball much larger than 

 the body of the Spider. 



The I'eet of the Spider, one of which is represented at 

 ]^o. 4, are curiously constructed. Each foot, when mag- 

 nified, is seen to be armed with strong horny claws, with 

 serrations on the under-surface. By this arrangement the 

 Spider is enabled to regulate the issue of its rope from the 

 spinnarets. Some have, in addition, a remarkable comb- 

 like claw, for the purpose of separating certain threads 

 which enter into the composition of their delicate webs. 



One of the most remarkable members of the family, the 

 Argyroneta aquatlca^ Diving Spider, weaves itself a curious 

 little bell-shaped globule, which it takes with it to the 

 bottom of the water, whitlier it retires to devour its prey. 

 ]!^ot\vithstanding its aquatic habits, this, like the rest of 

 its order, is fitted only fur aerial respiration ; it therefore 

 fills its miniature balloon Avith air, which it carries down 

 with it entangled amongst the hairs of its hody. This 

 closely resembles the earliest diving-bells. 



Mr. Quekett recommended the following as a simple 

 method of obtaining a jDcrfect system of tracheal tulDes 

 from the larvae of insects : — A small opening having been 

 made in the body, it is to be placed in strong acetic acid, 

 which softens or decomposes all the viscera : the trachea 

 must then be well washed with a syringe, and removed 

 from the body, by cutting away the connexions of the 

 main trunks with the spiracles, by means of fine-pointed 

 scissors. For mounting, they should be floated on to the 

 glass-slide, and laid out in the position best adapted for 

 displaying them. If we wish to mount them in Canada 

 balsam, they should be allowed to dry upon the slide, 



